Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 32
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Gene ; : 145535, 2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33631240

RESUMO

Aluminum (Al) toxicity is an important factor in limiting peanut growth on acidic soil. The molecular mechanisms underlying peanut responses to Al stress are largely unknown. In this study, we performed transcriptome analysis of the root tips (0-1 cm) of peanut cultivar ZH2 (Al-sensitive) and 99-1507 (Al-tolerant) respectively. Root tips of peanuts that treated with 100 µM Al for 8 hours and 24 hours were analyzed by RNA-Seq, and a total of 8,587 differentially expressed genes (DEGs) were identified. GO and KEGG pathway analysis excavated a group of important Al-responsive genes related to organic acid transport, metal cation transport, transcription regulation and programmed cell death (PCD). These homologs were promising targets to modulate Al tolerance in peanuts. It was found that the rapid transcriptomic response to Al stress in 99-1507 helped to activate effective Al tolerance mechanisms. Protein and protein interaction analysis indicated that MAPK signal transduction played important roles in the early response to Al stress in peanuts. Moreover, weighted correlation network analysis (WGCNA) identified a predicted EIL (EIN3-like) gene with greatly increased expression as an Al-associated gene, and revealed a link between ethylene signaling transduction and Al resistance related genes in peanut, which suggested the enhanced signal transduction mediated the rapid transcriptomic responses. Our results revealed key pathways and genes associated with Al stress, and improved the understanding of Al response in peanut.

2.
J Basic Microbiol ; 61(2): 165-176, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33448033

RESUMO

Sugarcane/peanut intercropping is a highly efficient planting pattern in South China. However, the effects of sugarcane/peanut intercropping on soil quality need to be clarified. This study characterized the soil microbial community and the soil quality in sugarcane/peanut intercropping systems by the Illumina MiSeq platform. The results showed that the intercropping sugarcane (IS) system significantly increased the total N (TN), available N (AN), available P (AP), pH value, and acid phosphatase activity (ACP), but it had little effect on the total P (TP), total K (TK), available K (AK), organic matter (OM), urease activity, protease activity, catalase activity, and sucrase activity, compared with those in monocropping sugarcane (MS) and monocropping peanut (MP) systems. Both intercropping peanut (IP) and IS soils contained more bacteria and fungi than soils in the MP and MS fields, and the microbes identified were mainly Chloroflexi and Acidobacteria, respectively. Intercropping significantly increased the number of unique microbes in IS soils (68 genera), compared with the numbers in the IP (14), MS (17), and MP (16) systems. The redundancy analysis revealed that the abundances of culturable Acidobacteriaceae subgroup 1, nonculturable DA111, and culturable Acidobacteria were positively correlated with the measured soil quality in the intercropping system. Furthermore, the sugarcane/peanut intercropping significantly increased the economic benefit by 87.84% and 36.38%, as compared with that of the MP and MS, respectively. These results suggest that peanut and sugarcane intercropping increases the available N and P content by increasing the abundance of rhizospheric microbes, especially Acidobacteriaceae subgroup 1, DA111, and Acidobacteria.

3.
Physiol Plant ; 170(2): 218-226, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32479663

RESUMO

Melatonin is widely involved in plant growth and stress responses as a master regulator. Melatonin treatment alters the levels of endogenous nitric oxide (NO) and NO affects endogenous melatonin content. Melatonin and NO may induce various plant physiological behavior through interaction mechanism. However, the interactions between melatonin and NO in plants are largely unknown. The review presented the metabolism of endogenous melatonin and NO and their relationship in plants. The interactions between melatonin and NO in plant growth and development and responses to environmental stress were summarized. The molecular mechanisms of interaction between melatonin and NO in plants were also proposed.


Assuntos
Melatonina , Desenvolvimento Vegetal , Óxido Nítrico , Fenômenos Fisiológicos Vegetais , Plantas , Estresse Fisiológico
4.
BMC Biotechnol ; 20(1): 13, 2020 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-32111197

RESUMO

BACKGROUND: Intercropping, an essential cultivation pattern in modern agricultural systems, increases crop yields and soil quality. Cassava and peanut intercropping systems exhibit advantages in solar utilization and cadmium absorption, etc. However, the inner mechanisms need to be elucidated. In this study, Illumina MiSeq platform was used to reveal the rhizospheric microbes and soil quality in cassava/peanut intercropping systems, and the results provided a reference for the application of this method in studying other intercropping systems. RESULTS: Both intercropping cassava/peanut (IP) and intercropping peanut/cassava (IC) systems significantly increased available N, available K, pH value, and urease activity, comparing with that in monocropping cassava (MC) and monocropping peanut (MP) system. However, there were few effects on the total N, total P, total K, available P, organic matter, protease activity, catalase activity, sucrase activity, and acid phosphatase activity. Both IP and MP soils contained more bacteria and fungi than those in the IC and MC soils, which were mainly made of Proteobacteria and Actinobacteria. Intercropping remarkably increased the number of Nitrospirae in IP and IC soils comparing those in MC and MP soils. Redundancy analysis (RDA) revealed that the abundances of DA101, Pilimelia, and Ramlibacter were positively correlated to the soil quality. These results suggest that intercropping enhances the available nitrogen content of soil through increasing the quantity of rhizospheric microbes, especially that of DA101 and Pilimelia. CONCLUSIONS: The cassava/peanut intercropping system improves soil quality through increasing the available nitrogen content and abundance of DA101, Pilimelia, and Ramlibacter in the soil.


Assuntos
Agricultura/métodos , Arachis/crescimento & desenvolvimento , Bactérias/classificação , Fungos/classificação , Manihot/crescimento & desenvolvimento , Nitrogênio/metabolismo , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Produtos Agrícolas/crescimento & desenvolvimento , Fungos/crescimento & desenvolvimento , Fungos/isolamento & purificação , Sequenciamento de Nucleotídeos em Larga Escala , Filogenia , Potássio/metabolismo , Rizosfera , Análise de Sequência de DNA , Solo/química , Microbiologia do Solo
5.
BMC Genomics ; 21(1): 117, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32013881

RESUMO

BACKGROUND: Yam tuber is a storage organ, derived from the modified stem. Tuber expansion is a complex process, and depends on the expressions of genes that can be influenced by environmental and endogenous factors. However, little is known about the regulatory mechanism of tuber expansion. In order to identify the genes and miRNAs involved in tuber expansion, we examined the mRNAs and small RNAs in Dioscorea opposita (Chinese yam) cv. Guihuai 16 tuber during its initiation and expansion stages. RESULTS: A total of 14,238 differentially expressed genes in yam tuber at its expansion stage were identified by using RNA sequencing technology. Among them, 5723 genes were up-regulated, and 8515 genes were down-regulated. Functional analysis revealed the coordination of tuber plant involved in processes of cell events, metabolism, biosynthesis, and signal transduction pathways at transcriptional level, suggesting that these differentially expressed genes are somehow involved in response to tuber expansion, including CDPK, CaM, CDL, SAUR, DELLA, SuSy, and expansin. In addition, 541 transcription factor genes showed differential expression during the expansion stage at transcriptional level. MADS, bHLH, and GRAS were involved in cell differentiation, division, and expansion, which may relate to tuber expansion. Noteworthy, data analysis revealed that 22 known tuber miRNAs belong to 10 miRNA families, and 50 novel miRNAs were identified. The integrated analysis of miRNA-mRNA showed that 4 known miRNAs and 11 genes formed 14 miRNA-target mRNA pairs were co-expressed in expansion stage. miRNA160, miRNA396, miRNA535 and miRNA5021 may be involved in complex network to regulate cell division and differentiation in yam during its expansion stage. CONCLUSION: The mRNA and miRNA datasets presented here identified a subset of candidate genes and miRNAs that are putatively associated with tuber expansion in yam, a hypothetical model of genetic regulatory network associated with tuber expansion in yam was put forward, which may provide a foundation for molecular regulatory mechanism researching on tuber expansion in Dioscorea species.


Assuntos
Dioscorea/genética , Redes Reguladoras de Genes/genética , MicroRNAs/genética , Tubérculos/genética , RNA Mensageiro/genética , Transcriptoma/genética , Perfilação da Expressão Gênica/métodos
6.
Sci Rep ; 9(1): 9516, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31267033

RESUMO

Aluminum (Al) causes programmed cell death (PCD) in plants. Our previous studies have confirmed that nitric oxide (NO) inhibits Al-induced PCD in the root tips of peanut. However, the mechanism by which NO inhibits Al-induced PCD is unclear. Here the effects of NO on mitochondrial reactive oxygen species (ROS), malondialdehyde (MDA), activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), expression of alternative oxidase (AhAOX) and cytochrome oxidase (AhCOX) were investigated in peanut (Arachis hypogaea L.) root tips treated with Al. The results showed that Al stress induced rapid accumulation of H2O2 and MDA and increased the ratio of SOD/APX. The up-regulation of AhAOX and AhCOX expressions was not enough to inhibit PCD occurrence. Sodium nitroprusside (SNP, a NO donor) decreased the ratio of SOD/APX and eliminated excess H2O2 and MDA, thereby inhibiting Al-induced PCD in the root tips of peanut. The expression of AhAOX and AhCOX was significantly enhanced in Al-induced PCD treated with SNP. But cPTIO (a NO specific scavenger) supply had the opposite effect. Taken together, these results suggested that lipid peroxidation induced by higher levels of H2O2 was an important cause of Al-induced PCD. NO-mediated inhibition of Al-induced PCD was related to a significant elimination of H2O2 accumulation by decreasing the ratio of SOD/APX and up-regulating the expression of AhAOX and AhCOX.


Assuntos
Alumínio/toxicidade , Antioxidantes/metabolismo , Apoptose/efeitos dos fármacos , Arachis/metabolismo , Óxido Nítrico/metabolismo , Ascorbato Peroxidases/metabolismo , Análise por Conglomerados , Regulação para Baixo/efeitos dos fármacos , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Malondialdeído/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Nitroprussiato/farmacologia , Raízes de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Regulação para Cima/efeitos dos fármacos
7.
Plant Signal Behav ; 14(9): 1640566, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291833

RESUMO

Aluminum (Al) promotes programmed cell death (PCD) in plants. Although a lot of knowledge about the mechanisms of Al tolerance has been learned, how Al-induced PCD is regulated by nitric oxide (NO) is poorly understood. Mitochondrion is the regulatory center for PCD. We found that Al reduced the level of mitochondrial NO/H2O2, promoted the opening of mitochondrial permeability transition pore, decreased mitochondrial inner membrane potential (∆ψm), and increased caspase-like protease activity. NO-specific scavenger cPTIO enhanced these effects that were reversed by NO donor sodium nitroprusside. Our data suggest that NO suppresses Al-induced PCD by improving mitochondrial physiological properties.


Assuntos
Alumínio/toxicidade , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Mitocôndrias/metabolismo , Óxido Nítrico/metabolismo , Plantas/metabolismo , Mitocôndrias/efeitos dos fármacos
8.
Mol Biol Rep ; 46(1): 403-414, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30446960

RESUMO

The multidrug and toxic compound extrusion (MATE) protein family is a newly discovered family of secondary transporters that extrude metabolic waste and a variety of antibiotics out of the cell using an electrochemical gradient of H+ or Na+ across the membrane. The main function of MATE gene family is to participate in the process of plant detoxification and morphogenesis. The genome-wide analysis of the MATE genes in potato genome was conducted. At least 48 genes were initially identified and classified into six subfamilies. The chromosomal localization of MATE gene family showed that they could be distributed on 11 chromosomes except chromosome 9. The number of amino acids is 145-616, the molecular weight of proteins is 15.96-66.13 KD, the isoelectric point is 4.97-9.17, and they were located on the endoplasmic reticulum with having 4-13 transmembrane segments. They contain only two parts of the exons and UTR without introns. Some members of the first subfamily of potato MATE gene family are clustered with At2g04070 and they may be related to the transport of toxic compounds such as alkaloids and heavy metal. The function of the members of the second subfamily may be similar to that of At3g23560, which is related to tetramethylammonium transport. Some members of the third subfamily are clustered with At3g59030 and they may be involved in the transport of flavonoids. The fifth subfamily may be related to the transport of iron ions. The function of the sixth subfamily may be similar to that of At4g39030, which is related to salicylic acid transport. There are three kinds of conserved motifs in potato MATE genes, including the motif 1, motif 2, and motif 3. Each motif has 50 amino acids. The number of each motif is different in the gene sequence, of which 45 MATE genes contain at least a motif, but there is no motif in ST0015301, ST0045283, and ST0082336. These results provide a reference for further research on the function of potato MATE genes.


Assuntos
Proteínas de Transporte de Cátions Orgânicos/genética , Solanum tuberosum/genética , Sequência de Aminoácidos , Cromossomos de Plantas/genética , Sequência Conservada/genética , Éxons , Duplicação Gênica , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas/genética , Genes de Plantas/genética , Genoma de Planta/genética , Família Multigênica/genética , Proteínas de Transporte de Cátions Orgânicos/fisiologia , Filogenia , Proteínas de Plantas/genética
9.
Biometals ; 32(1): 1-9, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30387073

RESUMO

As gasotransmitter, nitric oxide (NO) and hydrogen sulfide (H2S) are involved in the regulation of plant tolerance to abiotic stresses. Aluminum (Al) toxicity triggers synthesis of NO and H2S and seriously affects plant growth and productivity. Exogenous NO and H2S alleviate Al toxicity in plants. However, the physiological and molecular mechanisms of NO and H2S in alleviating Al toxicity are very scattered. In this review, the advances in the effects of Al on the content of endogenous NO and H2S and the mechanisms of exogenous NO and H2S in alleviating Al toxicity in plants are summarized and discussed. The signaling pathway for the roles of NO and H2S in alleviating Al toxicity is also proposed.


Assuntos
Alumínio/farmacologia , Sulfeto de Hidrogênio/metabolismo , Óxido Nítrico/metabolismo , Plantas/efeitos dos fármacos , Alumínio/toxicidade , Sulfeto de Hidrogênio/farmacologia , Óxido Nítrico/biossíntese , Óxido Nítrico/farmacologia , Plantas/metabolismo
10.
Artigo em Inglês | MEDLINE | ID: mdl-30518096

RESUMO

Information concerning carbon reduction efficiency is of great significance to supply chain operations. Considering the impact of information asymmetry on the performance of low-carbon supply chain, we therefore analyze a chain system with a single product designer and a single manufacturer. The manufacturer owns information on carbon reduction efficiency, whereas the product designer only knows that the carbon reduction efficiency of the manufacturer is either high or low. To induce the manufacturer to reveal his true private information of carbon-reduction efficiency to the product designer, we devise the pooling and separating equilibrium models to compare the impacts of these two models on supply chain performance, respectively. We find that the high-efficiency manufacturer gets his first-best choice at the equilibrium decision in the separating model, and obtains the information rent in the pooling model. The information rent increases in the efficiency difference between the two emission-reduction types. Additionally, we examine how the probability of the high (or low)-efficiency manufacturer being chosen impacts on both the profits of chain members and carbon-reduction levels. The research provides a reference for companies about how to cooperate with partner who possess private information of carbon emissions.


Assuntos
Pegada de Carbono/economia , Conservação de Recursos Energéticos/métodos , Revelação , Indústria Manufatureira/economia , China , Conservação de Recursos Energéticos/economia , Eficiência Organizacional , Política Ambiental , Indústria Manufatureira/organização & administração , Modelos Econômicos
11.
Ecotoxicol Environ Saf ; 157: 403-408, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29653374

RESUMO

With the increase of industrial wastes, sewage irrigation, chemical fertilizers and pesticides, metal contamination is increasingly serious. How to reduce the environmental risk has become a compelling problem in cultivated land. As a gaseous signal molecule, hydrogen sulfide (H2S) is involved in multiple plant responses to toxic metal stress. Metal stress rapidly triggers endogenous H2S production and exogenous H2S alleviates metal toxicity in plants. To elucidate the role of H2S in metal tolerance, the physiological and molecular mechanisms of H2S in alleviating metal toxicity is necessary to be reviewed. Here, the latest progress on endogenous H2S metabolism and the role of H2S in plant responses to toxic metal stress were summarized and discussed. The mechanisms of exogenous H2S in alleviating metal toxicity is proposed.


Assuntos
Sulfeto de Hidrogênio/metabolismo , Metais Pesados/toxicidade , Plantas/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Metais Pesados/análise , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo
12.
Opt Lett ; 43(3): 515-518, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29400829

RESUMO

In this Letter, the characteristics of the AlGaN-based near-ultraviolet light-emitting diodes with a band-engineering last quantum barrier (LQB) were analyzed experimentally and numerically. The experimental results show that the peak wavelengths of UV-LEDs are around 368 nm with a full width at half-maximum of 12-14 nm, and the optical and electrical properties are improved by using an AlxGa1-xN LQB with a gradually decreasing Al content. The designed LQB can reduce the forward voltage from 4.35 to 4.29 V and markedly enhance LOP by 47.4% at an injection current of 200 mA, compared with the original structure. These improvements are mainly attributed to less electron leakage and higher hole injection efficiency, resulting from the weakened polarization field in the electron-blocking layer (EBL) and LQB, as well as the alleviation of the band bending at the EBL/LQB interface.

13.
Artigo em Inglês | MEDLINE | ID: mdl-29466281

RESUMO

Reducing carbon emissions, including emission abatement outsourcing at the supply-chain level, is becoming a significant but challenging problem in practice. Confronting this challenge, we therefore break down the practice to focus on a low-carbon supply chain consisting of one supplier, one manufacturer and one third-party emission-reducing contractor. The contractor offers a carbon reduction service to the manufacturer. In view of the increasing proportion of Greenhouse Gases (GHG) emissions and absence of carbon reduction policies in developing countries, we adopt the prospect of consumers' low-carbon preferences to capture the demand sensitivity on carbon emission. By exploiting the Mean-Variance (MV) model, we develop a supply chain game model considering risk aversion. Comparing the supply chain performances of the cases under risk neutrality and risk aversion, we investigate the impact of the risk aversion of the supplier and the manufacturer on the low-carbon supply chain performances, respectively. We show that the risk aversion of chain members will not influence the relationship underlain by the profit-sharing contract between the manufacturer and contractor, whereas they may extend the supplier's concerning range. Although the manufacturer's risk aversion has a positive impact on the wholesale price, interestingly, the supplier's impact on the wholesale price is negative. Furthermore, we propose a contract to coordinate the risk-averse low-carbon supply chain by tuning the aversion levels of the supplier and the manufacturer, respectively. Through numerical study, we draw on managerial insights for industrial practitioners to adopt a low carbon strategy potentially by managing the risk attitudes along the supply chain channel.


Assuntos
Carbono/provisão & distribução , Serviços Terceirizados/organização & administração , Comércio , Comportamento do Consumidor , Serviços Terceirizados/economia , Risco , Gestão de Riscos
14.
Methods Mol Biol ; 1743: 65-71, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29332286

RESUMO

Mitochondria play a crucial role in programmed cell death (PCD) in plants. In most cases of mitochondria-dependent PCD, cytochrome c (Cyt c) released from mitochondria due to the opening of mitochondrial permeability transition pore (MPTP) and the activation of caspase-like proteases. Here we describe the analytic methods of mitochondrial markers of PCD including mitochondria isolation, mitochondrial membrane permeability, mitochondrial inner membrane potential, Cytc release, ATP, and mitochondrial reactive oxygen species (ROS).


Assuntos
Apoptose , Biomarcadores , Mitocôndrias/genética , Mitocôndrias/metabolismo , Trifosfato de Adenosina/metabolismo , Arachis/genética , Arachis/metabolismo , Permeabilidade da Membrana Celular , Citocromos c/metabolismo , Peróxido de Hidrogênio/metabolismo , Potencial da Membrana Mitocondrial , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo
15.
Nitric Oxide ; 74: 47-55, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29353007

RESUMO

Aluminum (Al) stress alters nitric oxide (NO) and induces programmed cell death (PCD) in plants. Recent study has shown that NO inhibits Al-induced PCD. However, the mechanism of NO inhibiting Al-induced PCD has not been revealed yet. Here, we investigated the behavior of mitochondria during Al-induced PCD suppressed by NO in peanut. Seedlings of peanut was grown hydroponically in a controllable growth room. The mitochondrial physiological parameters were determined spectrophotometrically. The expression of AhANT and AhHsp70 was determined by quantitative RT-PCR. Al-induced cell death rapidly in peanut root tips is mitochondria-dependent PCD. There was a significantly negative relationship between PCD and mitochondrial NO/H2O2 level. Compared with Al treatment alone, the addition of NO donor sodium nitroprusside (SNP) increased the ratio of NO/H2O2, down-regulated AhANT expression and inhibited the opening of mitochondrial permeability transition pore (MPTP), up-regulated AhHsp70 expression and increased mitochondrial inner membrane potential (ΔΨm), reduced cytochrome c (Cyt c) release from mitochondria and caspase 3-like protease activity, while the effect of NO specific scavenger cPTIO supplement was opposite. NO suppresses Al-induce PCD in peanut root tips by improving mitochondrial physiological properties.


Assuntos
Alumínio/farmacologia , Arachis/citologia , Arachis/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Óxido Nítrico/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/efeitos dos fármacos , Arachis/metabolismo , Morte Celular/efeitos dos fármacos , Mitocôndrias/metabolismo , Raízes de Plantas/metabolismo
16.
Plant Cell Rep ; 37(3): 387-392, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29177845

RESUMO

Proline accumulation plays an important role in the response and adaptation of plants to abiotic stress. Gaseous signaling molecules such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are involved in complicated events of cell signaling. However, the regulatory mechanisms of gaseous signaling molecules on proline synthesis and degradation are still unclear. This review summarized the biosynthesis and degradation of proline. The role of gaseous signaling molecules and their cross-talk on proline metabolic regulation in plants was discussed along with the future perspectives.


Assuntos
Monóxido de Carbono/metabolismo , Sulfeto de Hidrogênio/metabolismo , Óxido Nítrico/metabolismo , Plantas/metabolismo , Prolina/metabolismo , Transdução de Sinais , Adaptação Fisiológica , Redes e Vias Metabólicas , Modelos Biológicos , Estresse Fisiológico
17.
ACS Appl Mater Interfaces ; 9(49): 43386-43392, 2017 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-29164860

RESUMO

It is widely believed that the lack of high-quality GaN wafers severely hinders the progress in GaN-based devices, especially for defect-sensitive devices. Here, low-cost AlN buffer layers were sputtered on cone-shaped patterned sapphire substrates (PSSs) to obtain high-quality GaN epilayers. Without any mask or regrowth, facet-controlled epitaxial lateral overgrowth was realized by metal-organic chemical vapor deposition. The uniform coating of the sputtered AlN buffer layer and the optimized multiple modulation guaranteed high growth selectivity and uniformity of the GaN epilayer. As a result, an extremely smooth surface was achieved with an average roughness of 0.17 nm over 3 × 3 µm2. It was found that the sputtered AlN buffer layer could significantly suppress dislocations on the cones. Moreover, the optimized three-dimensional growth process could effectively promote dislocation bending. Therefore, the threading dislocation density (TDD) of the GaN epilayer was reduced to 4.6 × 107 cm-2, which is about an order of magnitude lower than the case of two-step GaN on the PSS. In addition, contamination and crack in the light-emitting diode fabricated on the obtained GaN were also effectively suppressed by using the sputtered AlN buffer layer. All of these advantages led to a high output power of 116 mW at 500 mA with an emission wavelength of 375 nm. This simple, yet effective growth technique is believed to have great application prospects in high-performance TDD-sensitive optoelectronic and electronic devices.

18.
J Hazard Mater ; 333: 285-292, 2017 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-28371714

RESUMO

It had been reported that Aluminum (Al) stress altered nitric oxide (NO) concentration and induced programmed cell death (PCD) in plants. However, the relationship between NO and PCD occurrence under Al stress is unclear. The results showed that cell death induced by Al was significant negative correlation with the inhibition of Al on root elongation growth in peanut. AlCl3 at 100µmolL-1 induced DNA ladder, chromatin condensation, typical apoptotic chromatin condensation staining with DAPI, apoptosis related gene Hrs203j expression and caspase3-like protease activation in peanut root tip cells, and showed that Al-induced cell death in peanut root tip cells was a typical PCD. Exogenous NO donor sodium nitroprusside (SNP) at 200µmolL-1 inhibited Al-induced PCD occurrence, but NO specific scavenger cPTIO aggravated PCD production. It suggests that NO is a negative regulator of Al-induced PCD in peanut root tips.


Assuntos
Alumínio/toxicidade , Apoptose/efeitos dos fármacos , Arachis/efeitos dos fármacos , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico/fisiologia , Nitroprussiato/farmacologia , Raízes de Plantas/efeitos dos fármacos , Adaptação Fisiológica , Apoptose/genética , Arachis/genética , Arachis/fisiologia , Caspase 3/metabolismo , Cromatina/metabolismo , Ativação Enzimática , Genes de Plantas , Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento
19.
Front Physiol ; 8: 1037, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29311970

RESUMO

It has been reported that nitric oxide (NO) is a negative regulator of aluminum (Al)-induced programmed cell death (PCD) in peanut root tips. However, the inhibiting mechanism of NO on Al-induced PCD is unclear. In order to investigate the mechanism by which NO inhibits Al-induced PCD, the effects of co-treatment Al with the exogenous NO donor or the NO-specific scavenger on peanut root tips, the physiological properties of antioxidants systems and cell wall (CW) in root tip cells of NO inhibiting Al-induced PCD were studied with two peanut cultivars. The results showed that Al exposure induced endogenous NO accumulation, and endogenous NO burst increased antioxidant enzyme activity in response to Al stress. The addition of NO donor sodium nitroprusside (SNP) relieved Al-induced root elongation inhibition, cell death and Al adsorption in CW, as well as oxidative damage and ROS accumulation. Furthermore, co-treatment with the exogenous NO donor decreased MDA content, LOX activity and pectin methylesterase (PME) activity, increased xyloglucan endotransglucosylase (XET) activity and relative expression of the xyloglucan endotransglucosylase/hydrolase (XTH-32) gene. Taken together, exogenous NO alleviated Al-induced PCD by inhibiting Al adsorption in CW, enhancing antioxidant defense and reducing peroxidation of membrane lipids, alleviating the inhibition of Al on root elongation by maintaining the extensibility of CW, decreasing PME activity, and increasing XET activity and relative XTH-32 expression of CW.

20.
Nitric Oxide ; 42: 40-3, 2014 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-25178167

RESUMO

Whether carbon monoxide (CO) exerts toxic or protective effect is dependent on the concentration and location of CO in animals. Similarly, it has been increasingly evident that CO also is involved in diverse physiological processes in plants, from seed germination and dormancy to stomatal closure to regulation of multiple environmental stresses. In this review, we focus on CO synthesis and the role of CO in plant responses to abiotic stresses, such as salinity, drought, cadmium and mercury. In general, abiotic stresses induce CO production in plants. CO can alleviate oxidative damage by improving the activities of antioxidative enzymes and antioxidant metabolism. In addition, cross talk between CO signaling and other signaling molecules including nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) also is discussed.


Assuntos
Monóxido de Carbono/metabolismo , Plantas/metabolismo , Transdução de Sinais , Estresse Fisiológico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...